This invention pertains to an internal combustion engine control system adapted to control an ignition system or a fuel injection system for a four cycle internal combustion engine by means of an electronic control unit using a microcomputer and also pertains to an apparatus for practicing the system.
A four cycle internal combustion engine comprises a plurality of cylinders, a crank shaft rotationally driven by pistons moving in the cylinders, respectively, a cam shaft driving an air supply valve and an exhaust valve rotated in synchronization with the crank shaft at half a revolution rate of the crank shaft and an ignition system to ignite each of the cylinders in accordance with ignition signals therefor whereby a combustion cycle of four strokes including an explosion stroke, an exhaust stroke, an intake or suction stroke and a compression stroke is repeated to rotate the crank shaft thereby.
In order to sufficiently draw an output power out of the four cycle internal combustion engine, improve on fuel consumption and enhance purification of the exhaust gas, an ignition position of the internal combustion engine (a rotary angle position of the crank shaft at which an ignition operation is made) and a supply amount of fuel are required to be controlled in a highly precise manner in accordance with various control conditions such as a revolution rate (r.p.m) of the engine.
To this end, the latest four cycle internal combustion engine comprises a fuel injection system including an injector (an electro-magnetic fuel injection valve) provided for the respective cylinders, a fuel pump to supply a fuel to the injector and an injector drive circuit to supply a drive current to the injector and also a contactless ignition system whereby an electronic control unit (ECU) including a microcomputer controls the fuel injector system and the ignition system.
The injector for the fuel injection system comprises an injector body having a fuel injection port at a leading end thereof, a solenoid (an electromagnet) disposed within the injector body and a valve adapted to open the fuel injection port while the predetermined drive current is supplied to the solenoid whereby the fuel is supplied from the fuel pump to the injector body under predetermined pressure. The injector is mounted on an intake pipe of the engine, for example and serves to inject the fuel through the fuel injection port by opening the valve while the drive current is supplied to the solenoid from the injector drive circuit. The fuel injected within the intake pipe is combined with air entering the intake pipe through a throttle valve and supplied within the cylinders when intake valves thereof are opened.
Although an injection amount of the fuel from the injector is based on the product of the time during which the valve is opened and the fuel pressure provided by the fuel pump, it is generally determined on the injection time (a signal width of an injection instruction signal) because the fuel pressure is kept constant by a pressure regulator. Accordingly, in the internal combustion engine in which the fuel is supplied by the fuel injection system, the amount of the fuel supplied to the engine has been controlled by adjusting the signal width of the injection instruction signal.
In case that the fuel is injected into the intake pipe of the four cycle internal combustion engine, it is generally known that the fuel is desirably injected over the exhaust stroke and the intake stroke of the engine for precisely controlling the fuel consumption and the component of the exhaust gas. Accordingly, a position where the injection instruction signal is supplied to the injector drive circuit (a position where the fuel injection starts) should be set at a proper position within a scope of the rotary angle of the crank shaft corresponding to the exhaust stroke.
The contactless ignition system for igniting the internal combustion engine comprises an ignition plug mounted on each of the cylinders of the engine, an ignition coil having a secondary coil connected to the ignition plug for each of the respective cylinders and an ignition drive circuit to give an abrupt change in a primary current of the ignition coil in accordance with the ignition signals for the respective cylinders for inducing an igniting high voltage across the secondary coil of the ignition coil at the ignition position of the internal combustion engine (the rotary angle position of the crank shaft).
In general, the ignition coil is provided for every cylinder of the internal combustion engine, but one ignition coil is provided for a set of two cylinders having their ignition positions provided in a manner far away to each other at an crank angle of 360xc2x0 in some internal combustion engines having an even number of cylinders such as two or four cylinders. For instance, in the four cycle four cylinder internal combustion engine, the ignition is made in order of the first, third, fourth and second cylinders. In this case, the first and fourth cylinders having the ignition positions far away from each other at the crank angle of 360xc2x0 are as a first set of cylinders while the second and third cylinders are as another set of cylinders. Thus, there are provided two ignition coils including a first ignition coil for the first and fourth cylinders and a second ignition coil for the second and third cylinders. The secondary coils of the ignition coils have both ends connected to the non-grounding terminals of the ignition plugs for the two corresponding cylinders.
In case that the common one ignition coil is provided for the two cylinders having the ignition position far away from each other at the crank angle of 360xc2x0, the coil is referred as to xe2x80x9csimultaneous ignition coilxe2x80x9d, a secondary coil of which induces the igniting high voltage to be applied across the two ignition plugs of the two cylinders. In this case, the ignition operation (the operation of spark discharging the high voltage through the ignition plugs) is simultaneously made in the two cylinders, but in the four cycle internal combustion engine, one of the two cylinders having the ignition positions far away from each other at the crank angle of 360xc2x0 is at a normal ignition position when another cylinder is at an end of the exhaust stroke where the spark of another cylinder can never contribute to the ignition of the fuel. Thus, it will be noted that the operation of the engine has no trouble even though the two cylinders having the ignition position far away from each other at the crank angle of 360xc2x0 are simultaneously ignited.
A capacitor discharge type circuit and a current interruption type circuit are known as the ignition drive circuit provided at the primary side of the ignition coil. The capacitor discharge type ignition drive circuit comprises an igniting capacitor provided at the primary side of the ignition coil to be charged at one polarity at a position advanced relative to the ignition position and a primary current controlling switch turned on when the ignition signal is given to discharge the charge of the capacitor through the primary coil of the ignition coil whereby the abrupt change in the primary current of the ignition coil is generated by discharging the igniting capacitor to induce the igniting high voltage.
The current interruption type ignition drive circuit comprises a power source to supply the primary current to the ignition coil and a primary current controlling switch turned on by the ignition signal at the position advanced relative to the ignition position. The ignition drive circuit makes the primary current flow through the ignition coil when it receives the ignition signal and interrupts the primary current controlling switch when the ignition signal is extinguished at the ignition position whereby the igniting high voltage is induced in the secondary coil of the ignition coil. As the current interruption type ignition drive circuit are used a battery type one having a battery used for the power source and a generating coil type one having a generating coil for the power source provided in a magneto generator driven by the internal combustion engine.
The capacitor discharge type ignition drive circuit and the current interruption type ignition drive circuit are different from each other in a process of response to the ignition signal. More particularly, since the capacitor discharge type ignition drive circuit turns on the primary current controlling switch when the ignition signal is received to discharge the igniting capacitor to make the ignition operation, the timing when the ignition signal is generated corresponds to the ignition position, but since the current interruption type ignition drive circuit begins to conduct the primary current into the primary coil when the ignition current is received and interrupts the primary current when the ignition signal is extinguished to make the ignition operation, the timing when the ignition signal is extinguished corresponds to the ignition position.
Although either of the two ignition drive circuits may be used for the internal combustion engine to which the invention should be applied, the current interruption type ignition drive circuit having the battery used for the power source may be used as the ignition drive circuit for many four cycle internal combustion engine. Therefore, the case in which the current interruption type ignition drive circuit having the battery used for the power source is used will be explained later.
In case that the current interruption type ignition drive circuit having the battery used for the power source is used, there should be controlled a conduction start position (a position where the ignition signal is generated) to start the conduction of the primary current through the ignition coil and a conduction end position (a position where the ignition signal is extinguished) to interrupt the primary current.
The electronic control unit may comprise a CPU to arithmetically operates the revolution rate of the engine on the period of occurrence of the pulses generated at the particular rotary angle position of the crank shaft of the engine and to arithmetically operate the aforementioned conduction start position, the conduction end position (the ignition position) and the fuel injection time on the obtained revolution rate and the control conditions detected by various sensors.
The conduction start position is arithmetically operated as a time (a number of clocks to be counted) taken for the crank shaft to rotate to the conduction end position from a reference position of each of the cylinders (a position of 65xc2x0 prior to the top dead center of the compression stroke) set at the position fully advanced relative to the top dead center in the compression stroke of each of the cylinders (the rotary angle position when the piston of each of the cylinders reaches the top dead center). Similarly, the conduction end position (the ignition position) is arithmetically operated as a time required for the crank shaft to rotate from the conduction start position to the conduction end position.
The electronic control unit starts a conduction timer (a timer to measure the conduction start position by counting clock pulses) for every cylinder when the reference position therefor is detected and begins to measure the arithmetically obtained conduction start position. Also, it starts to inject the fuel from the injector for each of the cylinders when the reference position for each of the cylinders is detected and to start an injection timer (a timer to measure a fuel injection time) to begin to measure the fuel injection time.
When the conduction timer measures the conduction start position, the primary current starts to flow through the ignition coil for each of the cylinders and at the same time an ignition timer (a timer to measure the ignition position by counting the number of clock pulses) start to measure the ignition position. When the ignition timer measures the ignition position, the primary current through the ignition coil for each of the cylinders is interrupted to make the ignition operation of each of the cylinders. Also, when the injection timer completes to measure the fuel injection time, the injection of the fuel from the injector for each of the cylinders stops.
As aforementioned, the electronic control unit requires the informations on the reference position set for each of the cylinders in order to measure the conduction start position for the primary current through the ignition coil and the position where the injection of the fuel from the injector stops.
The ignition position cannot be obtained immediately when the engine should start because it takes time for the ignition position to be arithmetically operated and therefore the startability of the engine cannot be avoided from being deteriorated. Furthermore, since the revolution rate of the engine largely changes due to variation in the strokes of the engine immediately after the engine starts, it is hard to arithmetically operate the ignition position. Accordingly, it is desirable that in order to improve the startability of the engine by starting the ignition operation as soon as the starting operation of the engine begins, the ignition operation is made at the previously set constant position, but not at the ignition position determined by the arithmetical operation. Thus, the electronic control unit requires a signal for detecting the ignition position in the extremely low revolution range of the engine (referred to as xe2x80x9clow revolution ignition positionxe2x80x9d herein just below).
The aforementioned control system is adapted to mount on the crank shaft the crank shaft sensor for generating the pulses having the different polarities at the reference position and the low revolution ignition position for each of the cylinders to apply to the electronic control unit the signals obtained from the crank shaft sensor.
The crank shaft sensor sequentially generates the reference position detection pulse and the low revolution ignition position detection pulse for each of the cylinders, but even though the pulses are input to the electronic control unit, the unit cannot judge for which of the cylinders the input pulses are. Therefore, a cam shaft sensor is mounted on a cam shaft to generate one reference judgement pulse when the cam shaft rotates every one revolution and which of the cylinders a series of signals generated from the crank shaft sensor are for is judged on the reference judgement pulse.
In the four cycle internal combustion engine control system of the prior art, in case that the number of the cylinders of the internal combustion engine is two or four, the pulser coils having half the number of the cylinders are provided on the crank shaft sensor so that the pulses generated by each of the pulser coils at the reference position and the pulses generated by each of the pulser coils at the low revolution ignition position are input through the waveform shaping circuit to the CPU, respectively.
In case that the number of the cylinders is three, three pulser coils are provided so that the pulses generated by each of the pulser coils at the reference position and the pulses generated by each of the pulser coils at the low revolution ignition position are input through the waveform shaping circuit to the CPU, respectively.
In this manner, the prior internal combustion engine control system requires many pulser coils provided on the crank shaft sensor and in addition many waveform shaping circuits provided in the electronic control unit. Thus, the construction of the apparatus is disadvantageously expensive as well as complicated and large-sized.
If the ignition operation is adapted to be not made in the extremely low revolution range where the reference judgement pulse cannot be detected, then the single pulser coil would be desirably provided in the crank shaft sensor, which causes the construction of the apparatus to be simplified. However, if the ignition operation is not made in the extremely low revolution range, the startability of the engine cannot be avoided from being deteriorated because a cranking revolution rate is required to be higher when the engine starts.
In case that a vehicle driven by the internal combustion engine is one having the engine which should be avoided from stopping against the driver""s will such as an outerboard engine, a snow-mobile or the like, the engine desirably continues to be driven as much as possible even though a part of the control system is abnormally operated. However, in case that only one pulser coil is provided in the crank shaft sensor, the ignition operation and the fuel injection operation cannot be made when no signal is generated from the cam shaft sensor due to its disconnection so that which of the cylinders the reference position detection pulse is for cannot be judged. This disadvantageously prevents the engine from being effectively operated.
Accordingly, it is an object of the invention to provide an internal combustion engine control system and an apparatus therefor adapted to make an ignition operation with a single pulser coil provided in a crank shaft sensor even in case that no signal can be detected from a cam shaft sensor whereby the startability of the engine is not deteriorated and the construction of the apparatus is simplified.
It is another object of the invention to provide an internal combustion engine control system and an apparatus therefor adapted to continue to drive the engine even in case that no output can be detected from a cam shaft sensor due to some trouble.
One aspect of the present invention is applied to an internal combustion engine control system to control an ignition system for a four cycle multi-cylinder internal combustion engine.
In the internal combustion engine control system, there are provided a crank shaft sensor mounted on a crank shaft of the internal combustion engine to generate a low revolution ignition position detection signal of pulse wave at a low revolution ignition position of each of cylinders set near a top dead center in a compression stroke of each of the cylinders and to generate a reference position detection pulse at a reference position of each of the cylinders set at a position advanced relative to the low revolution ignition position of each of the cylinders, a cam shaft sensor mounted on a cam shaft of the internal combustion engine to generate a reference judgement pulse at a set rotary angle position of the cam shaft once per one revolution of the cam shaft and ignition position arithmetical operation means to arithmetically operate an ignition position for each of the cylinders on the predetermined control conditions, there are accomplished the step of simultaneously making an ignition operation in all of the cylinders at a position where the crank shaft sensor generates each of low revolution ignition position detection signals under the condition of being unable to detect any reference judgement pulse from the cam shaft sensor, the step of judging which of the cylinders a series of reference position detection pulses are one detecting the reference position for from a generation order of the series of the reference position detection pulses after the reference position detection pulses are generated when the reference judgement pulses is detected and the step of starting a measurement of the ignition position of each of the cylinders arithmetically operated by the ignition position arithmetical operation means at a position where the judged reference position detection pulse for each of the cylinders is generated to make the ignition operation at each of the cylinders when the thus arithmetically operated ignition position for each of the cylinders is measured.
Another aspect of the present invention is applied to an internal combustion engine control system to control an ignition system and a fuel injection system for a four cycle multi-cylinder internal combustion engine having a fuel supplied by the fuel injection system having an injector provided for each of cylinders.
In this internal combustion engine control system, there are provided a crank shaft sensor mounted on a crank shaft of the internal combustion engine to generate a low revolution ignition position detection signal of pulse wave at a low revolution ignition position of each of cylinders set near a top dead center in a compression stroke of each of the cylinders and to generate a reference position detection pulse at a reference position of each of the cylinders set at a position advanced relative to the low revolution ignition position of each of the cylinders, a cam shaft sensor mounted on a cam shaft of the internal combustion engine to generate a reference judgement pulse at a set rotary angle position of the cam shaft once per one revolution of the cam shaft, ignition position arithmetical operation means to arithmetically operate an ignition position for each of the cylinders on the predetermined control conditions and fuel injection time arithmetical operation means to arithmetically operate a fuel injection time of the injector for each of the cylinders and there are accomplished the step of starting an injection of the fuel from the injectors for all of the cylinders at a position where the crank shaft sensor generates each of the reference position detection pulse under the condition of being unable to detect any reference judgement pulse from the cam shaft sensor to inject the fuel from the corresponding injector for a set time, the step of simultaneously making an ignition operation in all of the cylinders at a position where the crank shaft sensor generates each of low revolution ignition position detection signals under the condition of being unable to detect any reference judgement pulse from the cam shaft sensor, the step of judging which of the cylinders a series of reference position detection pulses are one detecting the reference position for from a generation order of the series of the reference position detection pulses after the reference position detection pulses are generated when the reference judgement pulses are detected, the step of starting an injection of the fuel from the injector for each of the cylinders at a position where the judged reference position detection pulse for each of the cylinders is generated and stopping the injection of the fuel when the fuel injection time arithmetically operated by the fuel injection time arithmetical operation means lapses and the step of starting a measurement of the ignition position of each of the cylinders arithmetically operated by the ignition position arithmetical operation means at a position where the judged reference position detection pulse for each of the cylinders judged by the reference position detection judgement means is generated and making the ignition operation at each of the cylinders when the thus arithmetically operated ignition position for each of the cylinders is measured.
In case that the invention is applied to an internal combustion engine control apparatus to control an ignition system for a four cycle multi-cylinder internal combustion engine, the control apparatus comprises a crank shaft sensor, a cam shaft sensor and an electronic control unit (ECU).
The control apparatus of the invention is characterized by simultaneously making an ignition operation in all of the cylinders at a position where the crank shaft sensor generates each of low revolution ignition position detection signals under the condition of being unable to immediately generate any reference judgement pulse from the cam shaft sensor, which will occur when a crest value of an output pulse from the cam shaft sensor is too low due to the revolution rate of the internal combustion engine within the extreme low revolution range or when a reluctor on a rotor of the cam shaft sensor moves beyond a magnetic pole position of a signal generator when the start operation of the engine begins or under the condition of being unable to detect any reference judgement pulse generated from the cam shaft sensor, which will occur when a wiring for applying an output of the cam shaft sensor to the electronic control unit is disconnected, for example.
To this end, the crank shaft sensor used for the invention is mounted on the crank shaft of the internal combustion engine and so constructed as to generate a low revolution ignition position detection signal of pulse waveform at a low revolution ignition position set near a top dead center (a rotary angle position of the crank shaft when a piston of each of the cylinders reaches the top dead center) in a compression stroke of each of the cylinders and a reference position detection pulse at a reference position of each of the cylinders set at a position advanced relative to the low revolution ignition position of each of the cylinders. The cam shaft sensor is mounted on a cam shaft of the internal combustion engine and so constructed as to generate a reference judgement pulse at a rotary angle position set at a predetermined rotary angle position of the cam shaft once per one revolution of the cam shaft.
The electronic control unit includes urgent ignition signal supply means to supply an ignition signal to the ignition system whereby an ignition operation is simultaneously made in all of the cylinders at a position where the crank shaft sensor generates each of the low revolution ignition position detection signals under the condition of being unable to detect any reference judgement pulse from the cam shaft sensor, reference position detection pulse judgement means to judge which of the cylinders a series of reference position detection pulses are one detecting the reference position for from a generation order of the series of the reference position detection pulses after the reference judgement pulses are generated when the reference judgement pulses is detected, ignition position arithmetical operation means to arithmetically operate an ignition position for each of the cylinders under predetermined control conditions and constant ignition position control means to start a measurement of the ignition position of each of the cylinders arithmetically operated by the ignition position arithmetic measurement means at a position where the reference position detection pulse for each of the cylinders judged by the reference position pulse judgement means is generated and to make the ignition operation in each of the cylinders when the thus arithmetically operated ignition position for each of the cylinders is measured.
In case that the number of cylinders of the internal combustion engine is four, the four cylinders are divided into two sets of two cylinders having their ignition positions provided in a manner far away from each other at an crank angle of 360xc2x0 and both of the two cylinders of each of the cylinder sets are simultaneously ignited. The crank shaft sensor comprises a rotor rotationally driven by a crank shaft and having two reluctors provided at an equal angle distance corresponding to the two sets of cylinders, respectively and a single signal generator to generate pulses of different polarities when each of the reluctors on the rotor at a front edge and at a rear edge as viewed in the rotational direction, respectively;
In this case, a relation of position between each of the reluctors on the rotor and the signal generator is so set that the pulse generated when the signal generator detects the front edge of the reluctor corresponding to each of the cylinder sets and the pulse generated when the signal generator detects the rear edge of the reluctor corresponding to each of the cylinder sets become the reference position detection pulse and the low revolution ignition position detection pulse for each of cylinder sets, respectively.
In the four cycle four-cylinder internal combustion engine, if the four cylinders are simultaneously ignited when every low revolution ignition position detection signal for each of the cylinders is generated, a mixture gas is burnt in the cylinder having the ignition period to produce a torque to transfer the cylinder to an explosion stroke. One of the three cylinders having no ignition period is at an end of the explosion stroke and the remaining two of them are at an end of an exhaust stroke and at an end of intake stroke, respectively. Since the combustion is already finished in the cylinder being at the explosion stroke, no trouble occurs even though the ignition operation is made. Since no combustion is made in the cylinder being at the end of the exhaust stroke, no trouble also occurs even though a spark is generated. The fuel flows into the cylinder being at the end of the intake stroke, but the mixture gas will be never ignited and therefore combustion will hardly be extended because of the piston of the cylinder being near a bottom dead center. Even if the mixture gas is ignited, there will not occur such a torque as prevents the activation of the engine. Thus, in case all the four cylinders are ignited when the low revolution ignition position detection signal is generated, the ignition will be wastefully done in the cylinders other than the cylinder being at the ignition period and the engine can be started without any trouble because the rotation of the engine is adversely not affected by the wasteful ignition.
When the reference judgement pulse is detected, there is judged which of the cylinders a series of pulses generated by the crank shaft sensor correspond to. Thus, the ignition operation can be made at the position arithmetically operated by the CPU and therefore the engine can be driven without any trouble on the constant operation thereof.
As aforementioned, in the invention, since the ignition operation is simultaneously made in all the cylinders at the position where each of the low revolution ignition position detection signal is generated under the condition of being unable to detect any reference judgement pulse, such a sensor as sequentially generates pulses at the reference position and the low revolution ignition position of the series of cylinders may be used as the crank shaft sensor. Accordingly, the crank shaft sensor may have only one pulser coil provided therein, which causes the construction of the crank shaft sensor to be simplified. Since a circuit to input the output of the crank shaft sensor to the CPU may comprise only two circuits including a circuit to convert the reference position detection pulse into a signal having a waveform which can be recognized by the CPU and a circuit to convert the low revolution ignition position detection pulse into a signal having a waveform which can be recognized by the CPU, the construction of the electronic control unit can be more simplified than that of the prior art.
Although, in the aforementioned construction, only the ignition system is controlled, the invention may be applied to a four cycle four-cylinder internal combustion engine control apparatus which is adapted to control a fuel injection system as well as the ignition system. In this case, a crank shaft sensor is so constructed to generate the low revolution ignition position detection signal at the low revolution ignition position of each of the cylinders set near the top dead center in the compression stroke of each of the cylinders and to generate the reference position detection pulse at the reference position of each of the cylinders set at a position advanced relative to the low revolution ignition position of each of the cylinders and set at the position suitable for starting the injection of the fuel from the injector of each of the cylinders.
In this case, there is provided a electronic control unit including urgent fuel injection control means to apply to the fuel injection system a fuel injection instruction signal to start an injection of the fuel from the injectors for all of the cylinders at a position where the crank shaft sensor generates each of the reference position detection pulse under the condition of being unable to detect any reference judgement pulse from the cam shaft sensor because the revolution rate of the internal combustion engine is within a range of extreme low revolution of the internal combustion engine to inject the fuel from the respective injectors for a set time, urgent ignition control means to apply to an ignition system an ignition signal to simultaneously make an ignition operation in all of the cylinders at a position where the crank shaft sensor generates each of low revolution ignition position detection signals under the condition of being unable to detect any reference judgement pulse from the cam shaft sensor, reference position detection pulse judgment means to judge which of the cylinders a series of reference position detection pulses are one detecting the reference position for from a generation order of the series of the reference position detection pulses generated by the crank shaft sensor after the reference position detection pulses are generated, fuel injection time arithmetical operation means to arithmetically operate a fuel injection time (a time for which the fuel is injected from the injector) of the injector for each of the cylinders under predetermined control conditions, ignition position arithmetical operation means to arithmetically operate an ignition position for each of the cylinders under the predetermined control conditions, constant fuel injection control means to start an injection of the fuel from the injector for each of the cylinders at a position where the reference position detection pulse for each of the cylinders judged by the reference position detection pulse judgement means is generated and to stop the injection of the fuel when the fuel injection time arithmetically operated by the fuel injection arithmetical operation means lapses and constant ignition position control to start a measurement of the ignition position of each of the cylinders arithmetically operated by the ignition position arithmetical operation means at a position where the reference position detection pulse for each of the cylinders judged by the reference position detection pulse judgement means is generated and to make the ignition operation at each of the cylinders when the thus arithmetically operated ignition position for each of the cylinders is measured.
With the internal combustion engine control apparatus constructed as aforementioned, although the fuel is simultaneously injected from the injectors for all the cylinders under the condition of being unable to detect any reference judgment pulse, the fuel is never excessively supplied to the respective cylinders by properly adjusting the drive current supplied to a pump motor of a fuel pump so as to regulate the injection amount of the fuel from the respective injectors in a predetermined manner whereby no problem occurs in the operation of the engine.
The invention may be applied to a control apparatus to control a four cycle three-cylinder internal combustion engine.
In this case, there are provided a crank shaft sensor including a rotor rotationally driven by the crank shaft of the internal combustion engine and having three reluctors provided at a distance of 120xc2x0 angle corresponding to the three cylinders, respectively and a single signal generator to generate pulses of different polarities when each of the reluctors on the rotor at a front edge and at a rear edge as viewed in the rotational direction, respectively is detected and a relation of position between each of the reluctors on the rotor and the signal generator being set so as to generate a reference position detection pulse and a low revolution ignition position detection pulse when the signal generator detects the front edge and the rear edge of the reluctor corresponding to each of the cylinders at a reference position of each of the cylinders set at a position advanced relative to the position of top dead center in the compression stroke of each of the cylinders and at a low revolution ignition position of each of cylinders set near the top dead center in a compression stroke of each of the cylinders, respectively and a cam shaft sensor to generate a reference judgement pulse once per one revolution of the cam shaft in the same manner as aforementioned.
In this case, an electronic control unit includes urgent ignition signal supply means to supply an ignition signal to the ignition system so that an ignition operation is simultaneously made in all of the cylinders when the signal generator of the crank shaft sensor detects the rear edge of each of the reluctors as viewed in the rotational direction to generate the pulse under the condition of being unable to detect any reference judgement pulse output by the cam shaft sensor, reference position detection pulse judgement means to judge which of the cylinders a series of reference position detection pulses sequentially generated are one detecting the reference position for by distinguishing the generation order of the series of the reference position detection pulses obtained by the crank shaft sensor after the reference judgement pulses are generated under the condition of being able to detect the reference judgement pulses, ignition position arithmetical operation means to arithmetically operate an ignition position of each of the cylinders under predetermined control conditions and constant ignition position control means to start a measurement of the ignition position of each of the cylinders arithmetically operated by the ignition position arithmetical operation means at a position where the reference position detection pulse for each of the cylinders judged by the reference position detection judgement means is generated and to make the ignition operation in each of the cylinders when the thus arithmetically operated ignition position of each of the cylinders is measured.
In case that the internal combustion engine is consisted of three cylinders, the adjacent cylinders are spaced from each other at an angle distance of 240xc2x0. Thus, with the reluctors provided on the rotor of the crank shaft sensor at the angle distance of 120xc2x0 as aforementioned to generate the low revolution ignition signals for every 120xc2x0 rotation so as to make the simultaneous ignition operation in all of the three cylinders, a wasteful spark occurs at the beginning of the compression stroke of each of the cylinders and then the ignition operation is made at the low revolution ignition position set at the end of the compression stroke. In this case, when the wasteful spark occurs at the beginning of the compression stroke, the piston is located near the bottom dead center where the ratio of compression is low and as a result, the ignition operation will lead to the combustion of the mixture with extremely low probability. Thus, since the mixture will be actually ignited by the second ignition made at the end of the compression stroke, the engine can start without any problem.
The fuel injection system as well as the ignition system may be also controlled by the invention in case that it is applied to the three-cylinder internal combustion engine as aforementioned.
In this case, the electronic control unit includes urgent fuel injection control means to apply an injection instruction signal to the fuel injection system so as to simultaneously start an injection of the fuel from the injectors for all of the cylinders when the signal generator of the crank shaft sensor detects the front edge as viewed in the rotational direction to generate a pulse under the condition of being unable to detect any reference judgement pulse output by the cam shaft sensor to inject the fuel from the injectors for a set time, urgent ignition signal supply means to apply an ignition signal to the ignition system so as to simultaneously make an ignition operation in all of the cylinders when the signal generator of the crank shaft sensor detects the rear edge as viewed in the rotational direction to the crank shaft sensor to generate a pulse under the condition of being unable to detect any reference judgement pulse output by the cam shaft sensor, reference position detection pulse judgment means to judge which of the cylinders a series of reference position detection pulses are one detecting the reference position for by distinguishing the generation order of the series of the pulses output by the crank shaft sensor after the reference judgement pulses is generated, fuel injection time arithmetical operation means to arithmetically operate a fuel injection time of the injector for which the fuel is injected therefrom for each of the cylinders under the predetermined control conditions, ignition position arithmetical operation means to arithmetically operate an ignition position of each of the cylinders under the predetermined control conditions, constant fuel injection control means to apply an injection instruction signal to the fuel injection system to start an injection of the fuel from the injector for each of the cylinders at a position where there is generated the reference position detection pulse for each of the cylinders judged by the reference position detection pulse judgment means and to stop the injection of the fuel from each of the injectors when the fuel injection time arithmetically operated by the fuel injection arithmetical operation means lapses and constant ignition position control means to apply an ignition signal to the ignition system so as to start a measurement of the ignition position of each of the cylinders arithmetically operated by the ignition position arithmetical operation means at a position where there is generated the reference position detection pulse for each of the cylinders judged by the reference position detection pulse judgement means and to make the ignition operation in each of the cylinders when the ignition position of each of the cylinders arithmetically operated by the ignition position arithmetical operation means is measured.
Each of the reluctors on the rotor of the crank shaft sensor is formed so as to have a polar arc angle of 60xc2x0 and the reference position of each of the cylinders is set at a position advanced by an angle of 65xc2x0 relative to a top dead center of a compression stroke of each of the cylinders. The low revolution ignition position of each of the cylinders is set at a position advanced by an angle of 5xc2x0 relative to the top dead center of the compression stroke of each of the cylinders.
The invention can be also applied to a control apparatus to control a four cycle six-cylinder internal combustion engine.
In this case, the six cylinders are divided into three cylinder sets, respective one of which includes two cylinders having an ignition position far away from each other at a crank angle of 360xc2x0. The control apparatus comprises a crank shaft sensor including a rotor rotationally driven by the crank shaft of the internal combustion engine and having three reluctors provided at a distance of 120xc2x0 angle corresponding to the three cylinder sets, respectively and a single signal generator to generate pulses of different polarities when each of the reluctors on the rotor at a front edge and at a rear edge as viewed in the rotational direction, respectively is detected, respectively and a relation of position between each of the reluctors on the rotor and the signal generator being set so as to generate a reference position detection pulse and a low revolution ignition position detection pulse when the signal generator detects the front edge and the rear edge of the reluctor corresponding to each of the cylinder sets at a reference position advanced relative to a top dead center of a compression stroke of each of the cylinder sets and at a low revolution ignition position of each of the cylinder sets set near the top dead center in the compression stroke of each of the cylinder sets, respectively and a cam shaft sensor mounted on a cam shaft of the internal combustion engine to generate a reference judgement pulse at a set rotary angle position of the cam shaft once per one revolution of the cam shaft.
The electronic control unit includes urgent ignition signal supply means to supply an ignition signal to the ignition system so that an ignition operation is simultaneously made in all of the cylinders when the signal generator of the crank shaft sensor detects the rear edge of each of the reluctors as viewed in the rotational direction to generate the pulse under the condition of being unable to detect any reference judgement pulse from the cam shaft sensor, reference position detection pulse judgement means to judge which set of the cylinders a series of reference position detection pulses are one detecting the reference position for from a generation order of the series of the reference position detection pulses obtained by the crank shaft sensor after the reference judgement pulses are generated when the reference judgement pulses is detected, ignition position arithmetical operation means to arithmetically operate an ignition position for each of the cylinder sets under predetermined control conditions and constant ignition position control means to apply an ignition signal to the ignition system so as to start a measurement of the ignition position of each of the cylinder sets arithmetically operated by the ignition position arithmetical operation means at a position where there is generated the reference position detection pulse for each of the cylinder sets judged by the reference position detection pulse judgement means and to make the ignition operation in each of the cylinder sets when the thus arithmetically operated ignition position for each of the cylinder sets is measured.
In case that the four cycle six-cylinder internal combustion engine having a fuel injection system is controlled by the invention, the electronic control unit includes urgent fuel injection control means to apply an injection instruction signal to the fuel injection system so as to simultaneously start an injection of the fuel from the injectors for all of the cylinders at a position where the signal generator of the crank shaft sensor detects the front edge as viewed in the rotational direction to generate a pulse under the condition of being unable to detect any reference judgement pulse from the cam shaft sensor to inject the fuel from the injectors for a set time, urgent ignition signal supply means to apply the ignition signal to the ignition system so as to simultaneously make an ignition operation in all of the cylinders at a position where the signal generator of the crank shaft sensor detects the rear edge as viewed in the rotational direction to the crank shaft sensor to generate a pulse under the condition of being unable to detect any reference judgement pulse from the cam shaft sensor, reference position detection pulse judgment means to judge which of the cylinder sets a series of reference position detection pulses are one detecting the reference position for from a generation order of the series of the reference position detection pulses after the reference judgement pulses are generated when the reference judgement pulses is detected, fuel injection time arithmetical operation means to arithmetically operate a fuel injection time of the injector for each of the cylinder sets under the predetermined control conditions, ignition position arithmetical operation means to arithmetically operate an ignition position for each of the cylinder sets under the predetermined control conditions, constant fuel injection control means to apply an injection instruction signal to the fuel injection system so as to start an injection of the fuel from the injector for each of the cylinder sets at a position where there is generated the reference position detection pulse for each of the cylinder sets judged by the reference position detection pulse judgment means and to stop the injection of the fuel when the fuel injection time arithmetically operated by the fuel injection arithmetical operation means lapses and constant ignition position control to apply an ignition signal to the ignition system so as to start a measurement of the ignition position of each of the cylinder sets arithmetically operated by the ignition position arithmetical operation means at a position where there is generated the reference position detection pulse for each of the cylinder sets judged by the reference position detection pulse judgement means and to make the ignition operation in each of the cylinder sets when the ignition position for each of the cylinder sets arithmetically operated by the ignition position arithmetical operation means is measured.